Echinacea is a plant which originates from North America and Mexico; its therapeutical properties were well known to native Americans, who used it for healing wounds. Due to the fact that Echinacea was deemed able to increase the resistance to infections, during the first years of the last century its use for the treatment of local and generalised infections became widespread. Echinacea, in particular Echinacea angustifolia, is nowadays highly recommended for the treatment of influenza syndromes and in particular for the treatment of cold, for healing wounds and for the treatment of mycosis.
The general action is apparently due to the aspecific stimulation of the immune system and to the sensitisation of germs and pathogens to chemotherapeutics and antibiotics. The cicatrizing properties seem ascribable to the capacity of stabilizing hyaluronic acids through hyaluronidase inhibition exerted by one of the active principles contained in the plant, i.e. echinacoside, and to the massive macrophages activation induced by polysaccharides. In this way any foci of infection remain localised and accumulation of mucopolysaccharides and hystoplastic material necessary for reparative processes is favoured.
Therefore, to optimize the ability of Echinacea to stimulate the immune system, it would be desirable to provide extracts enriched in echinacoside and polysaccharides.
Among the active components of the plant there are also substances belonging to the class of alkylamides, in particular echinacein and isobutylamides of undecylenic and dodecaeninic acids which, besides exerting phytotherapeutic properties, inhibit cyclooxygenase (Planta Med. 60(1):37-40, 1994) and 5-lipoxygenase in vitro.
Alkylamides, although endowed with biological activity, proved highly toxic. In fact, studies carried out by the Applicant on murine splenocytes co-stimulated with concanavaline—A (Con-A) or lipopolysaccharide (LPS) in vitro, have evidenced that alkylamides are cytotoxic starting from concentrations of 1 μg/ml. Moreover, extracts containing 20% of alkylamides significantly inhibit intestinal motility in mice when administered i.p. at doses of 5 mg/ml or higher and have a DL50 of 236 mg/Kg when administered orally. Extracts containing 0.5% of alkylamides showed also toxic in subacute toxicity experiments, i.e. when the animals were treated for 30 days with pharmacologically active doses.
It would be therefore desirable to prepare Echinacea extracts with reduced alkylamides content and enriched in echinacoside and polysaccharides.
Echinacea extracts can be prepared with solvents, for example with ethanol-water mixtures or with supercritical carbon dioxide.
WO 01/22977 discloses a process for the preparation of Echinacea extracts containing standardized amounts of two or three components of the plant, in particular polysaccharides, cicoric acid and alkylamides. Each component is extracted from different parts of the plant with ethanol-water mixtures, for prolonged times. The extracts are subsequently combined for the preparation of pharmaceutical compositions.